Highly heat dissipative and abrasion resistant brake disk for bicycles

ABSTRACT

The present invention provides a highly heat dissipative and abrasion resistant bicycle brake disk. The brake disk is of a metal-based composite material, wherein the metal-based composite material includes a metal-containing material and 5% to 40% by volume of ceramic particles.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a bicycle brake disk, and moreparticularly to a bicycle brake disk made of a metal-based compositematerial.

[0003] 2. Description of the Prior Art

[0004] Stainless steel has high abrasion resistance therefore, bicyclebrake disks are generally made of stainless steel. However, stainlesssteel disks' adherence is reduced when wet. This causes slippage in theinterface between the brake disk and brake block in wet or rainyconditions, which in turn results in decreased braking force Inaddition, stainless steel has inferior heat dissipation. Thus, afterseveral successive brakings, the temperature of stainless steel brakedisks becomes relatively high. For mechanical braking, this hightemperature causes the brake disk to become pliable and deformed, alsoresulting in inadequate braking force. For fluid pressure (fluidhydraulic) braking, this high temperature causes the braking fluid toexpand and degrade, which also results in inadequate braking force

SUMMARY OF THE INVENTION

[0005] Therefore, the object of the present invention is to solve theabove-mentioned problems and to provide a bicycle brake disk with highheat dissipation and good abrasion resistance.

[0006] To achieve the above object, the highly heat dissipative andabrasion resistant bicycle brake disk of the present invention is madeof a metal-based composite material, wherein the metal-based compositematerial includes a metal-containing material and 5% to 40% by volume ofceramic particles.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007]FIG. 1 shows a perspective view of a bicycle brake disk of ametal-based composite material according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0008] The feature of the present invention is to use a metal-basedcomposite material to manufacture a bicycle brake disk different from aconventional brake disk made of stainless steel.

[0009] Refer to FIG. 1, showing a perspective view of a bicycle brakedisk of a metal-based composite material according to the presentinvention, The metal-based composite material includes a metalcontaining material and 5% to 40%, preferably 5% to 15% by volume, ofceramic particles. Suitable ceramic particles can be particles of SiC,Al₂O₃, TiB, or B₄C, preferably SiC particles or Al₂O₃ particles.Preferably, the ceramic particles have a particle size of 5 to 100 μm.

[0010] The metal-containing material suitable for use in the presentinvention can be aluminium, aluminium alloy, magnesium, magnesium alloy,titanium, or titanium alloy, preferably aluminum or aluminum alloy.Representative examples of the aluminum alloy include AlSi, AlSiCu,AlSiZn, AlSiMg, AlSiCuZn, AlZn, AlZnMg, AlGe, AlGeSi, AlCu, AlMn, AlMg,AlLi, AlSn, and AlPb, preferably AlMgSi.

[0011] In the present invention, using the metal-based compositematerial to manufacture a bicycle brake disk has the followingadvantages: light weight, good heat dissipation, and good abrasionresistance, explained below.

[0012] The metal-containing material used in the present invention ispreferably a metal or its alloy having a specific gravity of 1.7 to 4.6g/cm³. Thus, the brake disk thus manufactured is lightweight. Forexample, when the metal-containing material is aluminum or aluminumalloy, the specific gravity of the composite of aluminum or aluminumalloy combined with ceramic particles is approximately 2.8 g/cm³. Thespecific gravity of stainless steel is approximately 7.8 g/cm³. Thus,the bicycle brake disk made of the aluminum-based composite material ofthe present invention is approximately one third the weight of theconventional one of stainless steel.

[0013] The thermal conductivity of ceramic particles is about 100cal/cm·s·° C., about 1000 times the thermal conductivity of stainlesssteel (0.145 cal/cm·s·° C.). Therefore, the metal-based compositematerial combined with ceramic particles of the present invention has amuch higher thermal conductivity than stainless steel. Consequently,after several successive brakings, the bicycle brake disk of thealuminum-based composite material of the present invention has atemperature that is not too high For mechanical braking the brake diskbetter resists becoming pliable and deformed. For fluid pressurebraking, the brake disk better resists exceeding an acceptable workingtemperature. After several successive brakings, the brake disk stillprovides a good braking effect.

[0014] The hardness of ceramic particles is Hv 2550, higher than that ofstainless steel (Hv 400) by six times. When the bicycle brake disk madeof the aluminum-based composite material of the present invention isrubbed against a braking block, the harder ceramic particles are exposedto the surface, providing the brake disk of the invention with enhancedabrasion resistance.

[0015] The following examples are intended to illustrate the process andthe advantages of the present invention more fully without limiting itsscope, since numerous modifications and variations will be apparent tothose skilled in the art.

EXAMPLES

[0016] The following tests were taken according to DIN 79100 Part II5.6.4 “Breaking performance test”.

[0017] The brake disk of the present invention and a conventionalbicycle brake disk were subjected to separate testing. The tested brakedisk of the present invention was made of aluminum-based compositematerial (the aluminum alloy AlMgSi, and ceramic particles SiC). Theconventional brake disk was made of stainless steel. The brake disk wasrubbed against a bicycle braking block to generate a braking force.Testing methods included: (1) brake performance testing, (2) heatresistance testing, and (3) mechanical endurance testing.

EXAMPLE 1

[0018] Brake Performance Testing

[0019] (1) Test Content:

[0020] The testing speed (V) in dry conditions was 12.5 km/hr.

[0021] Before any measurements were taken, 10 trials were performed inorder to break in the brake blocks.

[0022] The force applied on the brake lever was not larger than 180 N.The running wheels were not allowed to lock up.

[0023] The average braking force (F) is the average value of the brakingforces determined. The average braking deceleration (a) is calculatedaccording to the formula: a=F/m.

[0024] The mass (m) is 100 kg for calculation.

[0025] (2) Test Requirement:

[0026] DIN 79100 Part II 5.6.4 requires that the braking deceleration indry conditions not be less than 3.4 m/s², and in wet conditions, not beless than 2.2 m/s².

[0027] (3) Test Results:

[0028] The test results are shown in Tables 1 and 2.

[0029] For the braking test in dry conditions, the abrasion resistanceof the stainless steel brake disk is provided by its hardness. As to thealuminum-based composite brake disk, although the aluminum matrix issoft, once the ceramic particles are exposed to the surface, theseceramic particles can effectively withstand abrasion. Thus, the measuredabrasion resistance of the brake disc of either the aluminum-basedcomposite or stainless steel is very close.

[0030] For braking testing in wet conditions, the stainless brake discexhibits slippage in its interface with the braking block duringbraking. Thus, the braking force is low. The ceramic particles in thealuminum-based composite brake disc are much more easily exposed duringthe wet braking test. Thus, the aluminum-based composite brake diskexhibits higher braking force than a conventional stainless steel brakedisk when the same force is applied to the brake lever. TABLE 1 ForceAbrasion applied to Braking condition of the brake deceleration thebrake disc Brake disk type lever (N) (m/s²) after test Al-based 80 3.59no abrasion composite material Stainless steel 80 3.62 no abrasion

[0031] TABLE 2 Force Abrasion Applied to Braking condition of the brakedeceleration the brake disc Brake disk type lever (N) (m/s²) after testAl-based 60 2.59 no abrasion composite material Stainless steel 60 2.23no abrasion

EXAMPLE 2

[0032] Heat Resistance Testing

[0033] (1) Test content:

[0034] Braking power =225 W.

[0035] The test period was 2 runs of 15 minutes.

[0036] 10 releases of the brake were allowed during each run, and thetime of each release was not longer than 2 seconds.

[0037] Temperatures were determined during a total determination periodof 30 minutes, and the average temperature was calculated.

[0038] (2) Test Requirement:

[0039] The temperature of the clamp was not allowed to exceed 100° C.during the heat resistance test.

[0040] (3) Test Results:

[0041] The results are shown in Table 3.

[0042] The thermal conductivity of ceramic particles in thealuminum-based composite material-made brake disk is higher than that ofstainless steel by 1000 times, allowing them to provide high heatdissipation. As shown in Table 3, during the heat resistance testperiod, the average temperature of the aluminum-based composite brakedisk is lower than that of the stainless steel brake disk. TABLE 3 Brakedisk type Temperature of brake disc Al-based composite material 58° C.stainless steel 72° C.

EXAMPLE 3

[0043] Mechanical Endurance Testing

[0044] (1) Test Content:

[0045] The testing speed (V) was 12.5 km/hr. Deceleration was 2.2 m/s².

[0046] The test braked 3000 times, and each braking lasted for 2.5seconds.

[0047] Temperatures were regularly measured at an interval of 100 timesin the entire testing period. Average temperature was calculated.

[0048] (2) Test Requirement:

[0049] DIN 79100 Part II 5.6.4 requires that a braking system shouldpass 3000 brakings. After the test, the rims must withstand a force of300 N applied to the brake lever and 1.5 times the maximum tirepressure.

[0050] (3) Test Results:

[0051] The 3000 times endurance test can not only detect if the brakedisk can withstand long period of abrasion, but also detect its workingtemperature.

[0052] As shown in Table 4, the working temperature of thealuminum-based composite brake disk is only 68° C., and the disk suffersno abrasion after testing. This is because the ceramic particles providesuperior abrasion resistance and heat dissipation. The hardness of theceramic particles provides high abrasion resistance. Moreover, theceramic particles dissipate frictional heat through radiation, thusproviding good heat dissipation.

[0053] The allowable working temperature for a fluid pressure brake diskis 130° C. When the temperature exceeds 130° C., the fluid in the brakeexpands and forms bubbles, compromising braking force. During the entireendurance test, the aluminum-based composite brake disk of the presentinvention maintains low working temperatures. Thus, it is very suitablefor use as a brake disk for a fluid pressure brake, and the brakingforce can be maintained. TABLE 4 Abrasion condition of Brake disk thebrake disc after Brake disk type temperature test Al-based 68° C. noabrasion composite material stainless steel 95° C. no abrasion

[0054] The foregoing description of the preferred embodiments of theinvention has been presented for purposes of illustration anddescription. Obvious modifications or variations are possible in lightof the above teaching. The embodiments were chosen and described toprovide the best illustration of the principles of this invention andits practical application to thereby enable those skilled in the art toutilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the presentinvention as determined by the appended claims when interpreted inaccordance with the breadth to which they are fairly, legally, andequitably entitled.

What is claimed is:
 1. A bicycle brake disk of a metal-based compositematerial, wherein the metal-based composite material includes ametal-containing material and 5% to 40% by volume of ceramic particles.2. The brake disk as claimed in claim 1, wherein the ceramic particlesare particles of a material selected from the group consisting of Sic,Al₂O₃, TiB, and B₄C.
 3. The brake disk as claimed in claim 2, whereinthe ceramic particles are SiC particles or Al₂O₃ particles.
 4. The brakedisk as claimed in claim 3, wherein the ceramic particles are SiCparticles.
 5. The brake disk as claimed in claim 1, wherein the ceramicparticles have a particle size of 5 to 100 μm.
 6. The brake disk asclaimed in claim 1, wherein the metal-containing material has a specificgravity of 1.7 to 4.6 g/cm³.
 7. The brake disk as claimed in claim 1,wherein the metal-containing material is selected from the groupconsisting of aluminium, aluminium alloy, magnesium, magnesium alloy,titanium, and titanium alloy.
 8. The brake disk as claimed in claim 7,wherein the metal-containing material is aluminum.
 9. The brake disk asclaimed in claim 7, wherein the metal-containing material is aluminumalloy.
 10. The brake disk as claimed in claim 9, wherein the aluminumalloy is selected from the group consisting of AlSi, AlSiCu, AlSiZn,AlSiMg, AlSiCuZn, AlZn, AlZnMg, AlGe, AlGeSi, AlCu, AlMn, AlMg, AlLi,AlSn, and AlPb.
 11. The brake disk as claimed in claim 10, wherein thealuminum alloy is AlMgSi.